Developers plan to keep the sea at bay

Climate change could mean a 1.9-metre surge by 2100: but sea walls and barriers should prevent low-lying landmarks from being swamped.

Engineers of the Palm Jumeirah in Dubai factored in a possible sea level rise of 50cm in its design, plus an additional buffer to protect against tides.

ABU DHABI // With hundreds of billions of dirhams invested in developing the capital's low-lying, sandy islands, prudent measures have been taken to ensure the landmark projects do not one day disappear under the sea.

Abu Dhabi's 2030 plan shows an idyllic archipelago, with arched bridges stretching across still, turquoise waters, joining eco-villages and residential zones to cultural landmarks and the lofty towers of the financial district. But much of the natural land earmarked for development lies at less than two metres above sea level, meaning defences are essential, especially in light of increasingly pessimistic data on the extent sea levels may rise.

Last week, a report commissioned by the Environment Agency-Abu Dhabi said the UAE could lose up to six per cent of its populated and developed coastline by the end of the century because of rising sea levels, and unless adequate planning is taken the economic impact will be "unacceptably high". According to a study published in Proceedings of the National Academy of Sciences last month, the average global sea level may rise by as much as 1.9 metres before 2100, much more than previous forecasts.

From ambitious land-raising projects to sea walls and barriers, safeguards against the impact of climate change must be considered by any coastal development. The Abu Dhabi 2030 plan states: "The emerging reality of global warming and its potential to raise sea levels means all new waterfront development should be planning for higher water levels at their edge." Originally lying at about two metres above sea level, Saadiyat Island, where Abu Dhabi plans to create a US$27 billion (Dh99bn) cultural district, has undergone massive landscaping to protect it from rising tides.

Developers used 106 million tonnes of rock and dredged sand to raise the level of the land by as much as 13 metres on parts of the island, which now stands between four and 15 metres above sea level. "We have also built breakwaters to protect the three exposed museums on the water's edge," said Dominique Bombaert, the project manager for Jan De Nul, the Belgian company that undertook the massive job. The island is also relatively naturally sheltered from sea swells, he said.

Abu Dhabi's Tourism Development & Investment Company said in a statement it had "ensured that the development of Saadiyat Island has been conducted with potential sea level and climatic changes in mind". Many plans for the islands were also under way before the Urban Planning Council (UPC) was formed in 2007. But the council, which is organising the capital's development, has met developers and is "confident" they have taken sufficient measures.

Developers currently have no legal obligation to take into account the potential for rising tides, but the UPC is writing new guidelines to be published before the end of the year. The Abu Dhabi 2030 plan says developers should take into account a 75cm rise in sea levels. Neil Mallen, the UPC's planning manager for the environment, said most developers had taken "very safely conservative estimates. It's the prudent thing to do in the absence of any reliable, official information".

However, the UPC still estimates that property and infrastructure valued at $400m now in place would be put at risk by a half-metre rise in sea level. The economic impact is expected to rise exponentially as construction grows in line with the Abu Dhabi 2030 plan. Nakheel officials have said engineers of the Palm Jumeirah in Dubai factored in a possible sea level rise of 50cm in its design, plus an additional buffer to protect against tides, storm surges and high seas. The level of the island is a minimum of four metres above the top water level at high tide.

According to last week's report, a rise of one metre in the UAE, the most modest scenario presented as not unlikely, would put 1,155 square kilometres of the country's coast under water by 2050. A rise of nine metres the most dire scenario would see almost all of the capital and much of Dubai submerged. It is easier, and more pleasing to the eye, to engineer protection into a project rather than add it later, according to Dr Paul Ashley, who is responsible for environment practice at Mott MacDonald, a British engineering and development company that worked on several developments in Dubai Marina.

"You could always aid coastal protection by retrofitting, but doing that and keeping a development attractive to live in could be tricky," he said. Though its geography may make the UAE susceptible to the effects of a rising sea, the Arabian Gulf's shallow waters, with a maximum depth of 90 metres, mean it is far less prone to storm surges. "The reality with the Gulf is that it's a rather small, shallow water basin so the risk of storm surges and really sudden dramatic impact from sea-level rise is if anything a little less," Mr Mallen said.

Larger landmark projects, which have teams of experts working on preventive measures, are not as much a concern to the UPC as smaller developments that may not take into account the potential for increased flooding. "There's certainly been a massive investment in development on relatively low-level land, and it's a concern," Mr Mallen said. :[e-mail]